Forces

Question 1

Hooke’s Law

Answer 1

Force is directly proportional to EXTENSION, provided that the elastic limit has not been exceeded.

Question 2

Elastic limit

Answer 2

The point beyond which the spring does not return to its original length when the load is removed.

Question 3

Pressure

Answer 3

Pressure is force per unit area.

Question 4

Upthrust

Answer 4

Upthrust is the net vertical upward force exerted by the surrounding fluid when a body is submerged fully or partially in a liquid

Question 5

Frictional force.

Answer 5

Force exerted by one body on another body when two bodies
slide over one another.

It is caused by irregularities in the surfaces in mutual contact and depends on the surfaces in contact as well as how much they are pressed against each
other. It is the component of contact force along the surface of contact.

Question 6

Drag force

Answer 6

The frictional force experienced either by an object as it moves through a fluid or by a fluid as it moves over a surface.

Question 7

Tensile forces

Answer 7

Two forces acting in opposite directions on an object so as to tend to increase its length along the direction of the forces.

Question 8

Compressive forces

Answer 8

Two forces acting in opposite directions on an object so as to tend to reduce its length along the direction of the forces.

Question 9

Equilibrium.

Answer 9

1. No resultant force acting on the body in any direction
2. No resultant torque acting on the body about any point.

Question 10

Centre of gravity

Answer 10

The single point through which the entire weight of the body can be considered to act.

Question 11

Moment of a force

Answer 11

The product of the magnitude of the force and the perpendicular distance from the line of action of the force to the point.

Question 12

Couple

Answer 12

A couple consists of a pair of forces equal in magnitude but acting in opposite directions, whose lines of action are parallel but separate.

Question 13

Torque of a couple

Answer 13

The product of one of the forces and the perpendicular distance between the forces, where a couple consists of a pair of forces that are in equal in magnitude but acting in opposite directions whose lines of action are parallel but separate.

Question 14

Principle of Moments

Answer 14

When a system is in equilibrium, the sum of the clockwise moments about any point is equal to the sum of the anti-clockwise moments about the same point.